Ginkgolide compounds belong to terpenoids and are also known as ginkgo terpene lactones which are composed of sesquiterpene lactones and diterpene lactones. Moreover, they are an important active ingredient in leaves of ginkgo.
Ginkgolide C is a diterpene lactone compound, which was firstly separated from leaves of ginkgo by S. Furukawa in 1932, and was further separated and identified the chemical structure thereof by K. Nakanish, M. Maruyama and K. Okabe, et al. in 1967. Ginkgolide compounds have a molecular skeleton consisting of 20 carbon atoms and having 6 five-membered rings: 2 five-membered carbocyclic rings, 3 five-membered lactone rings, and 1 tetrahydrofuran ring, in which 2 five-membered carbocyclic rings are linked together in the form of a spiro ring, and the other rings are fused together, so as to form the following particular rigid cage stereochemical structure.
 R1R2R3Ginkgolide AOHHHGinkgolide BOHOHHGinkgolide COHOHOH
All the ginkgolides have a potent antagonist of platelet activating factor, and are a particular active ingredient in each part of ginkgo plant. The content of the ginkgolides is highest in the root bark of ginkgo, which is about three times of that in ginkgo leaves. The ginkgolide compounds are bitter white crystals with the melting point of about 300° C. Because a hydroxy group/hydroxy groups and several oxygen-containing ester groups are present in molecule, the ginkgolide compounds have higher polarity than common sesquiterpene and diterpene compounds, and are soluble in organic solvents such as ethanol, acetone, butanone, ethyl acetate, dimethyl sulfoxide and the like.
The ginkgolide compounds are very stable against concentrated acids and strong oxidants. After a ginkgolide compound is dissolved in concentrated nitric acid and then evaporated to dryness, the lactone thereof would not be destroyed. The ginkgolide compound comprises several lactone structures in molecule. The ginkgolide compound can be reacted with a base to produce a salt which is soluble in water. If the resulting salt is acidified with an acid, it will convert to the initial lactone which is insoluble in water but soluble in an organic solvent. Therefore, this property can be used for the extraction and separation of ginkgolides.
Currently, many studies are focused on the separation and purification of the ginkgolides from leaves of ginkgo, but there are few reports regarding the separation and purification of ginkgolides from root bark of ginkgo. The ginkgolides from leaves of ginkgo are generally obtained by extracted, separated on columns, and then further separated by a high performance liquid preparative chromatography to achieve a purity of 95%. That is, macroporous adsorptive resin only contributes to the removal of impurities and the enrichment in the process, but does not actually contribute to the purification. Moreover, the use of C18 column increases the process steps and production cost, so that the entire process for separation and purification is relatively complex, the yield is low, the cost is expensive, and a mass production is difficult to carry out. Only one patent application with application No. 201010294667.9, titled “A PROCESS FOR EXTRACTING GINKOGLIDES A AND C FROM ROOT BARK OF GINKGO”, relates to the separation and purification of ginkgolides from the root bark of ginkgo. However, the technical solution of the patent application can only obtain a mixture of Ginkgolides A and C, and cannot directly offer a high-purity Ginkgolide C.